This invention relates to a ventricular by-pass valve which is known in several countries and was originally designed in the United States of America in the year 1958. In the United States it is known as the Pudenz valve, in Japan as the Fuji valve, etc.
In the original design, adopted by several countries, the valve consists of a biconvex structure having an intermedium veil, these three elements being made from a silicon rubber elastomeric material having a connection toward the brain and another connection toward the heart or peritoneum. This mechanism ensures the outflow of cephalorachidian liquid when it has been retained in the brain causing hydrocephalus. The arrangement of the different elements comprised by the valve causes it to function as a one-way pump too, which, through outside handling, produces faster ejection of the brain liquid. Experience has demonstrated that notwithstanding its excellent operating characteristics, this design is capable of eventual collapse by the unpredictable action of forces originated by the elastomer itself and by negative pressure produced after the impelling force. This phenomenon can cause problems in the operation of the equipment.
Although the design has been known for more than 25 years and has had the preference of some investigators, many types of more complex and expensive by-pass valves were designed all over the world, but these are more easily obstructed.
Through the accumulated and published experience it was known that the old "Pudenz" design continued to be preferred, but keeping in greater or lesser degree, as an undesirable eventuality, the collapsing failure during use. Many investigators tried, by using different designs on the inclusion of various devices, to avoid the eventual collapse in the original design, but giving up other advantages of the original valve and exposing the valve to damage of its inner structure when carrying out punctures that are usually made to obtain samples of the cephalorachidian liquid. This background constitutes the basis for the studies which led to the present invention.